Issued Patents All Time
| Patent # | Title | Co-Inventors | Date |
|---|---|---|---|
| 6684910 | Multi-layered pipe | Jan Stoffelsma, Volker Koestring, Helmut Schroeder | 2004-02-03 |
| 4957793 | Waste pipe system comprising plastic pipe parts made of thermoplastic material with sound-proofing properties | Jurgen Graafmann | 1990-09-18 |
| 4572523 | Sealing joint and retaining ring for pipe grooved bell and straight spigot joint | Bernhard Lodder | 1986-02-25 |